Structural composites are materials that have generally been developed in attempts to combine desirable properties of two or more different types of materials. A common example of a composite is reinforced concrete, in which steel bars (rebar) are arranged within a concrete matrix. The rebar provides tensile strength to the composite, compensating for concrete's lower tensile strength. Another common example of a composite material is the material commonly referred to as “carbon fiber,” and more properly referred to as carbon fiber reinforced plastic, which is a reinforced plastic composite with a plastic material serving as a matrix material to bind reinforcing carbon fibers distributed throughout the plastic matrix material. Other reinforced plastic materials may include other reinforcing fibers or particles distributed throughout the plastic matrix. Typically, the properties of composite materials are a compromise of the individual materials that are combined to form the composite. For example, a carbon fiber reinforced plastic may be stronger that the plastic matrix material, but weaker than the individual carbon fibers. It also may be tougher than the carbon fibers, but not as tough as the plastic matrix material.
Ceramic matrix composite (CMC) materials have been developed with similar objectives, but have evolved in different ways to address certain material properties. CMC materials include a ceramic matrix material and a ceramic reinforcement material, where the reinforcement material is typically in the form of long fibers. In addition to adding some of their strength or other properties to the overall composite material, the reinforcing fibers may also interrupt crack propagation through the matrix material. Many ceramics are brittle in nature and cracking due to fatigue, impact, or thermal shock may be a primary weakness of ceramic materials.